Large parts of Britain remain at risk of further flooding as forecasters warn of more heavy rain.

The Met Office has extended its severe weather alert until Thursday morning, warning that the already saturated ground and swollen rivers in the south of England and Wales might not cope with more rain.

The yellow warning for rain - the lowest of the Met Office's three levels - forecasts "periods of heavy rain" in the south west of England and Wales for Wednesday and into Thursday with 30mm to 40mm falling in the wettest spots.

A Met Office spokesman said: "The public should be aware of the potential for further flooding, especially in the areas which have been affected recently.

"Given current sensitive hydrological conditions, there is a risk of further surface water flooding in Wales, and both river and surface water flooding in Cornwall, Devon and Somerset."

There are no longer any severe flood warnings in force tonight, the Environment Agency (EA) said, b ut 105 flood warnings urging people to be prepared for flooding remain in place across the country, including in Dorset, south Wiltshire, Hampshire and along the River Thames in Oxfordshire, while 195 low-level alerts have been issued.

Paul Mustow, flood risk manager at the EA, said: "The risk of flooding continues this week, with communities in the South West and South East urged to stay safe and sign up to free flood warnings."

The threat from the huge waves that have battered Britain for the past few days has receded, with students forced from their seafront homes in Aberystwyth allowed to return.

The threat posed by the tide was illustrated last night when the EA's flood siren in Dorset was sounded for the first time - warning of extreme danger to people and property.

The alarm was raised after waves breached Chiswell Beach in Portland and spray crashed over flood defences. Residents were back on alert this morning but high tide passed without incident.

Seven people have died and more than 1,700 homes and businesses have been flooded in England since the beginning of the Christmas period, with around 550 properties flooded since the new year. Some 140 properties have been flooded in Wales.

Flood defences protected 220,000 properties over the Christmas period and another 800,000 were protected during the coastal flooding in early December.

High winds over Christmas also left 250,000 homes without power, with some families waiting days for electricity to be restored.

Environment Secretary Owen Paterson yesterday said the Government was working closely with local councils, the insurance industry and others to ensure that people could quickly get the help they need.

Some areas of the country were focused on recovery after storms and flooding over the Christmas and new year period, while others remained at significant risk of floods, he told the Commons.

Mr Paterson admitted that a few energy network companies could have been quicker at restoring power to thousands of homes affected by the storms and floods over Christmas.

MPs have raised concerns at the Department of the Environment's ability to respond to emergencies, such as flooding, because of swingeing budget cuts.

The Environment, Food and Rural Affairs parliamentary committee said £500 million had been cut from Defra's budget since 2010 and a further £300 million was earmarked over the next two years.

Committee chairwoman Anne McIntosh said: "Ministers must clarify how further budget cuts over £300 million over the next coming two years will impact on the funding provided to these agencies and the ability of the department to respond to emergencies.

"Recent flooding events over the Christmas and new year period reinforce the committee's concerns about cuts to the Defra budget and how these will be realised."

The NFU called on the Government to ensure a balance between funding for large capital flood defence projects and river maintenance.

Deputy president Meurig Raymond said: "Without adequate funding being made available to maintain waterways, flooding problems will only increase."

The political row, which followed a Friends of the Earth challenge to Government claims that it was spending more than ever on flood defences, came as the misery continued for some communities.

Flooding in the Somerset Levels has left villages cut off and roads and buildings damaged, and waves of up to 27ft have been recorded at Land's End, Cornwall.

Waves at Portreath washed away a 100-year-old stone hut on the breakwater and at Porthcothan Bay, between Newquay and Padstow, a huge rock collapsed under the force of the waves.

Palmer's Brewery in Bridport was evacuated when scaffolding was struck by lightning for the second time in 12 months but beer production was not affected.

In Tewkesbury, Gloucestershire, business leaders stressed the town centre is "open for business" with all main routes open despite extensive flooding in the outskirts.

In London the Thames Barrier closed for the 11th successive tide and many rail passengers continued to face cancelled or delayed services because of the weather.

The AA said it had attended around 1,900 flood-related incidents since December 23 and warned motorists not to take any chances driving on flooded roads.

Searches have continued in south Devon for missing 18-year-old university student Harry Martin, who has not been seen since last Thursday after leaving his home to take photographs of the weather.

Police said specialist search teams and divers were checking areas that could not be accessed before and were revisiting other locations and plan to continue the hunt for the rest of the week.

Officials around the country have pleaded with people to keep away from coastal areas as dozens put their lives at risk by arriving to watch as the storm brought waves of up to 40ft high crashing on to land.

People were warned to keep away from cliffs in Hastings, East Sussex, after excessive rainfall, strong winds and high tides lead to a massive rock fall.

Friends of Harry Swordy, 27, who died after being washed out to sea off Cornwall on New Year's Day, have begun a StormHarry appeal on Twitter for the UK's bad weather to be named after him.

Mr Paterson later said: "With the continued risk of surface water flooding I chaired a further COBR meeting this afternoon to get an update on the current situation and to make sure that assistance is available to those affected.

"The Department for Communities and Local Government has met with councils to agree progress on the recovery and to make sure the right help is available to people in the aftermath of the recent storms.

"I would like to thank the Environment Agency, emergency services and local volunteers who have worked so hard to help people during the bad weather."